package com.program.utils;
import org.apache.shiro.crypto.hash.Md5Hash;
import org.apache.shiro.crypto.hash.SimpleHash;
import org.apache.shiro.util.ByteSource;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Base64;
import java.util.Base64.Encoder;
import java.util.Random;
import java.util.UUID;

public class EncryptUtils {

    public static String getAccessToken() {
        String token = UUID.randomUUID().toString().replaceAll("-", "") + "";
        try {
            MessageDigest md = MessageDigest.getInstance("md5");

            byte md5[] = md.digest(token.getBytes());
            Encoder encoder = Base64.getEncoder();

            return encoder.encodeToString(md5);

        } catch (NoSuchAlgorithmException e) {

            throw new RuntimeException(e);
        }
    }

    /**
     * shiro的MD5加密规则
     * @param password
     * @param salt
     * @return
     */
    public static final String shiroMD5(String password, String salt) {
        // 加密方式
        String hashAlgorithmName = Md5Hash.ALGORITHM_NAME;
        // 盐
        ByteSource byteSalt = ByteSource.Util.bytes(salt);
        // 密码
        Object source = password;
        // 加密次数
        int hashIterations = 1024;

        SimpleHash result = new SimpleHash(hashAlgorithmName, source, byteSalt, hashIterations);
        return result.toString();
    }

    /**
     * base64加密
     * @param content
     * @return
     */
    private static final char[] legalChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
            .toCharArray();
    public static String base64Encode(String content) {
        StringBuffer buf = null;
        try {
            byte[] data = content.getBytes("utf-8");
            int start = 0;
            int len = data.length;
            buf = new StringBuffer(data.length * 3 / 2);

            int end = len - 3;
            int i = start;
            int n = 0;

            while (i <= end) {
                int d = ((((int) data[i]) & 0x0ff) << 16) | ((((int) data[i + 1]) & 0x0ff) << 8)
                        | (((int) data[i + 2]) & 0x0ff);

                buf.append(legalChars[(d >> 18) & 63]);
                buf.append(legalChars[(d >> 12) & 63]);
                buf.append(legalChars[(d >> 6) & 63]);
                buf.append(legalChars[d & 63]);

                i += 3;

                if (n++ >= 14) {
                    n = 0;
                    buf.append(" ");
                }
            }

            if (i == start + len - 2) {
                int d = ((((int) data[i]) & 0x0ff) << 16) | ((((int) data[i + 1]) & 255) << 8);

                buf.append(legalChars[(d >> 18) & 63]);
                buf.append(legalChars[(d >> 12) & 63]);
                buf.append(legalChars[(d >> 6) & 63]);
                buf.append("=");
            } else if (i == start + len - 1) {
                int d = (((int) data[i]) & 0x0ff) << 16;

                buf.append(legalChars[(d >> 18) & 63]);
                buf.append(legalChars[(d >> 12) & 63]);
                buf.append("==");
            }
        } catch (Exception e) {
            // TODO: handle exception
        }

        return buf.toString();
    }

    private static int decode(char c) {
        if (c >= 'A' && c <= 'Z')
            return ((int) c) - 65;
        else if (c >= 'a' && c <= 'z')
            return ((int) c) - 97 + 26;
        else if (c >= '0' && c <= '9')
            return ((int) c) - 48 + 26 + 26;
        else
            switch (c) {
                case '+':
                    return 62;
                case '/':
                    return 63;
                case '=':
                    return 0;
                default:
                    throw new RuntimeException("unexpected code: " + c);
            }
    }

    /**
     * base64解密
     * @param str
     * @return
     */
    public static String base64Decode(String str) {

        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        try {
            decode(str, bos);
        } catch (IOException e) {
            throw new RuntimeException();
        }
        byte[] decodedBytes = bos.toByteArray();
        try {
            bos.close();
            bos = null;
        } catch (IOException ex) {
            System.err.println("Error while decoding BASE64: " + ex.toString());
        }
        return new String(decodedBytes);
    }

    private static void decode(String s, OutputStream os) throws IOException {
        int i = 0;

        int len = s.length();

        while (true) {
            while (i < len && s.charAt(i) <= ' ')
                i++;

            if (i == len)
                break;

            int tri = (decode(s.charAt(i)) << 18) + (decode(s.charAt(i + 1)) << 12) + (decode(s.charAt(i + 2)) << 6)
                    + (decode(s.charAt(i + 3)));

            os.write((tri >> 16) & 255);
            if (s.charAt(i + 2) == '=')
                break;
            os.write((tri >> 8) & 255);
            if (s.charAt(i + 3) == '=')
                break;
            os.write(tri & 255);

            i += 4;
        }
    }

    public static void main(String[] args) throws UnsupportedEncodingException {
        String content = "477897277575262208";
        System.out.println("加密之前：" + content);

        // 加密
        String jiami = base64Encode(content);
        System.out.println("加密后的内容：" + jiami);

        // 解密
        String jiemi = base64Decode(jiami);
        System.out.println("解密后的内容：" + jiemi);
    }
}
